西昆仑加里东期造山作用初探

DISCUSSION OF OROGENICS OF THE WESTERN KUNLUN MOUNTAINS DURING THE CALEDONIAN OROGENY

在西昆仑前山一带存在一个发育完全的加里东期碰撞造山带 ,该造山带代表了古秦—祁—昆大洋的消亡和两侧大陆的剧烈碰撞。古昆仑洋可能开始裂解于震旦纪 ,寒武纪达最大程度 ,奥陶纪开始向南俯冲消减 ,志留纪两侧陆块发生碰撞。其曼于特—库地蛇绿岩为其洋壳残片 ,北侧的塔里木板块南缘具被动边缘性质 ,南侧的西昆仑地块为活动边缘性质。同时有大量俯冲型、碰撞型和造山期后伸展型花岗岩侵入。

A well developed orogenic belt resulted from collisions during the Caledonian cycle is in the frontal of the western Kunlun. The orogenic belt has revealed the consuming old oceans of Qinling Qilianshan Kunlun and an intensive collision between the continental massives at both sides. The old Kunlun ocean started breaking in Sinian period, then more intensive shearing in the Cambrian period and finally underthrust and subducted toward south in the Ordovician period. In the Silurian period, the continental massives at the both sides collided, resulting in the Manyute Kudi ophiolite oceanic relics. The south margin of the Tarimu plate at the north side had the passive marginal features and the western Kunlun land mass at the south side has the active marginal features. Meanwhile, a lot of granite of subduction, collision and extending at late orogenic period intruded and the pink red molasses formation in the late Devonian period indicated the end of the process.